Pressure distribution in the wrist joint

Abstract

We performed a study to determine pressure distribution properties of the normal radio-carpal joint. A system was developed for measurement of the contact pressure within the wrist joint surfaces. The transducer was based on Fuji pressure-sensitive paper, which was inserted into the joint space through a dorsal capsular incision. The hand was then positioned using a jig that permitted free axial loading of the joint. Each of five specimens was tested in 36 positions combining flexion/extension with radio/ulnar deviation and supination/pronation. The transducers were analyzed for contact area, scapho-lunate contact area ratio, pressure, and centroid locations using a microcomputer-based video-imaging system. The scaphoid and lunate contact areas on the radius and triangular fibrocartilage were separate and distinct in all wrist positions. Together these contact areas accounted for a relatively small fraction of the total joint surface area (average contact area/total joint area = 0.206, SD = 0.0495). For an applied 103 Newton compressive load, the high pressure averaged 3.17 MPa (SD = 0.83 MPa). Overall, the scaphoid contact area was 1.47 times that of the lunate, although variations occurred with position, as in flexion, in which the scaphoid/lunate area ratio was 0.83. The high-pressure centroids of both scaphoid and lunate contact areas shifted palmarly from 20 degrees of flexion to 20 degrees of extension and then dorsally with further extension. The scaphoid-lunate intercentroid distance averaged 14.91 mm with a range of 10-20 mm.

Volar Fixed-Angle Plating of Distal Radius Extension Fractures: Influence of Plate Position on Secondary Loss of Reduction—A Biomechanic Study in a Cadaveric Model

“…5,13,34,37 The earlier-described biomechanic study shows that rigid fixation can be achieved by fixed-angle volar plating with subchondral screw placement.…”

“…Because we were using a distal forearm model the total load applied to the radius was about 640 N, because the ulna in this setting takes up 18% to 20% of the total load applied to the forearm. 25,[33][34][35] Based on the calculations of Putnam et al 23 an 800-N load to the forearm therefore corresponds to grip forces between 100 and 200 N. In osteoporotic bone, however, the forces necessary to cause postoperative radial shortening are probably even lower.…”

MRI-based modeling for evaluation of in vivo contact mechanics in the human wrist during active light grasp

“…Tencer et al (1988) reported radiocarpal contact area ratios data for 36 different forearm and wrist positions. For neutral radioulnar deviation, they reported the radioscaphoid to radiolunate contact area ratio as 3.72 with neutral flexion-extension and 2.19 with 201 of wrist extension.…”

The temporal response of the friction coefficient of articular cartilage depends on the contact area

“…Indeed, for human joints, contact areas of 50 mm 2 (the high end of values tested here, Fig. 2) are representative of finger and wrist joints, which typically experience stresses of 0-3 MPa (Tencer et al, 1988;Ateshian et al, 1995). For the patellofemoral joint, contact areas may be as high as 400 mm 2 , with peak contact stresses of 4.5 MPa under normal activities Huberti and Hayes, 1984).…”